EP0624633A2 - Copolymers self-crosslinking by contact with humidity and blends - Google Patents

Abstract

Essentially isocyanate-free, ketimine-free and aldimine-free, one-component sealing, adhesive or coating compositions which are self-curing under the action of atmospheric humidity, comprising a copolymer A composed of 50-99.8% by weight of a C1-C16-alkyl (meth)acrylate or vinyl ester of carboxylic acids of 1 to 20 carbon atoms a), 0.1-20% by weight of an unsaturated carboxylic acid anhydride b), 0.1-10% by weight of an Si-containing compound c) which is capable of undergoing hydrolysis, and 0-40% by weight of a further, copolymerisable unsaturated compound d) or containing a mixture of copolymers comprising 5-95% by weight, based on the mixture, of a copolymer B) composed of 50-99.9% by weight of a C1-C16-alkyl (meth)acrylate or vinyl ester of carboxylic acids of 1 to 20 carbon atoms a), 0-20% by weight of an unsaturated carboxylic acid anhydride b), 0.1-10% by weight of an Si-containing compound c) capable of undergoing hydrolysis, and 0-40% by weight of a further, copolymerisable unsaturated compound d) and 5-95% by weight, based on the mixture, of a copolymer C) composed of 50-99.9% by weight of a C1-C16-alkyl (meth)acrylate or vinyl ester of carboxylic acids of 1 to 20 carbon atoms a), 0.1-20% by weight of an unsaturated carboxylic acid anhydride b), 0-10% by weight of an Si-containing compound c) which is capable of undergoing hydrolysis, and 0-40% by weight of a further, copolymerisable unsaturated compound d), the K value of one of the copolymers B) or C) being from 12 to 40 and that of the other copolymer being from 30 to 70, and the K values of the two copolymers differing by at least 5 K value units, where the K value is measured according to DIN 53 726.

Description

The invention relates essentially to isocyanate-free, ketimine and aldimine-free, one-component sealants, adhesives or coating compositions which contain a copolymer A and are self-curing by the action of atmospheric moisture
50 - 99.8% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids with 1 to 20 C atoms a)
0.1-20% by weight of an unsaturated carboxylic anhydride b)
0.1-10% by weight of an Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
or
containing a mixture of copolymers containing
5 - 95 wt .-%, based on the mixture, of a copolymer B), built up from
50-99.9% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids having 1 to 20 C atoms a),
0-20% by weight of an unsaturated carboxylic anhydride b)
0.1-10% by weight of an Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
and
5 - 95 wt .-%, based on the mixture, of a copolymer C), built up from
50-99.9% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids having 1 to 20 C atoms a),
0.1-20% by weight of an unsaturated carboxylic anhydride b)
0-10% by weight of a Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
wherein the K value measured according to DIN 53 726 of one of the copolymers B) or c) is 12 to 40 and the other copolymers 30 to 70 and the K value of the two copolymers differs by at least 5 K value units.

The invention further relates to copolymers or mixtures of copolymers which are self-curing under atmospheric humidity.

One-component sealing compounds that are self-curing due to air humidity are stored in closed containers, e.g. Cartridges kept. You do not need to add a second component when using it. As soon as the container is opened or the sealant is pressed out of the cartridge, self-hardening begins due to the effects of atmospheric moisture.

Previously known sealing compounds which hardened by the action of atmospheric moisture contain a large number of isocyanate compounds as crosslinking agents. According to DE-A 39 13 168, isocyanates can be polymerized into polymers. Mixtures of diisocyanates or aldimines or ketimines with copolymers, which contain hydrolyzable Si compounds bound as regulators, are known from DE-A 40 38 939 as sealing compounds.

A disadvantage of sealing compounds containing isocyanate compounds which cure under atmospheric humidity is yellowing which can be observed, and in particular the formation of carbon dioxide during curing. The mechanical properties of the hardened sealing compounds are impaired by gas inclusions. Furthermore, the gas development precludes applications in which no increase in volume is to occur.

Other copolymers containing hydrolyzable Si compounds which are used in sealing or coating compositions are known from DE-A 39 07 991, DE-A 34 26 057 and EP-A 122 457.

In general, sealing or coating compounds are desirable that have a high tensile strength and good resilience after stress e.g. Have elongation, do not tend to yellowing and where there is no gas evolution.

The object of the invention was therefore to provide such masses.

The task was solved by the masses defined above.

The sealing, adhesive or coating compositions contain a copolymer A or a mixture of copolymers B) and C).

The copolymers contain as structural components C₁-C₁₆-alkyl (meth) acrylates a), unsaturated carboxylic anhydrides b), a hydrolysis-capable Si-containing compound c) and other polymerizable, unsaturated compounds d).

Preferred compounds a) are C₁-C₁₆-, particularly preferably C₁-C₈-alkyl (meth) acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, n- and isopropyl (meth) acrylate, n-butyl ( meth) acrylate and 2 ethylhexyl (meth) acrylate. In addition to the C₁-C₁₆ alkyl (meth) acrylates, compounds a) also include vinyl esters of carboxylic acids having 1 to 20 C atoms, such as vinyl laurate, vinyl stearate, vinyl propionate and in particular vinyl acetate, and mixtures thereof with C₁-C₁₆ alkyl (meth) acrylates into consideration.

Unsaturated carboxylic anhydrides b) preferably have 4 to 8, particularly preferably 4 or 5, carbon atoms. Examples include Maleic anhydride, itaconic anhydride and citraconic dianhydride and also cyclohexenedicarboxylic anhydride.

oder deren Gemische, wobei
R¹ für eine C₁-C₁₈-, vorzugsweise C₁-C₆-Alkylgruppe oder eine Phenylgruppe, R² für eine C₁-C₁₈-, vorzugsweise eine C₁-C₆-Alkylengruppe, eine Cyclohexylengruppe oder Phenylengruppe, Z für eine C₁-C₁₈-, vorzugsweise C₁-C₆-Alkylgruppe oder eine Phenylgruppe, X für eine radikalisch copolymerisierbare Gruppe und n für 0, 1 oder 2 steht. X steht bevorzugt für einen (Meth)acryl-, (Meth)acrylamid- oder Vinylrest.The Si-containing compounds capable of hydrolysis are preferably compounds of the general formula I.

or mixtures thereof, where
R¹ for a C₁-C₁₈-, preferably C₁-C Alkyl-alkyl group or a phenyl group, R² for a C₁-C₁₈-, preferably a C₁-C₆-alkylene group, a cyclohexylene group or phenylene group, Z for a C₁-C₁₈-, preferably C₁- C₆-alkyl group or a phenyl group, X is a radical copolymerizable group and n is 0, 1 or 2. X preferably represents a (meth) acrylic, (meth) acrylamide or vinyl radical.

For example, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-methacryloxypropyltris- (2-methoxyethoxy) silane, vinyltrimethoxysilane, vinyltris (methoxyethoxy) silane and in particular (meth) acryloxyltrylysiloxysiloxysiloxysiloxysilane,

Compounds of the formula I are incorporated as a monomer by copolymerization with the group X.

Compounds of the formula II are incorporated at the end of the polymer chain as regulators and, due to their regulating action, cause a reduction in the molecular weight and thus also in the K value.

Compounds d) are vinylaromatic compounds such as vinyltoluene, α- and p-styrene, α-butylstyrene, 4-n-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene, vinyl halides, preferably vinyl chloride and vinylidene chloride and non-aromatic Hydrocarbons with 2 to 8 carbon atoms and at least two olefinic double bonds such as butadiene, isoprene and chloroprene, and C₂-C₄ olefins, for example Ethylene.

Copolymer A is preferably composed of
70 - 99% by weight a),
0.1 - 12% by weight b),
0.1 - 8% by weight c) and
0 - 25% by weight d).

The K value of the copolymer A is preferably 20 to 60.

The K value is a relative viscosity number that is determined in accordance with DIN 53 726 at 25 ° C. It gives the flow rate of a mixture of 0.01 g of polymer in 1 ml of tetrahydrofuran (THF), relative to the flow rate of pure THF, and characterizes the average degree of polymerization of the polymer.

The glass transition temperature T _{g of} the copolymer A) is preferably -70 to +20, particularly preferably -50 to +20 and very preferably -40 to -10 ° C. The polymer is liquid above the T _g .

The glass transition temperature of the copolymer can be determined by conventional methods such as differential thermal analysis or differential scanning calorimetry (see, for example, ASTM 3418/82, so-called "midpoint temperature").

A preferred mixture containing copolymers B) and C) contains
20 to 80% by weight of copolymer B) and
20 to 80% by weight of copolymer C).

Copolymer B) is preferably composed of
70 - 99.9% by weight a),
0-10% by weight b),
0.1 - 8% by weight c) and
0 - 25% by weight d).

Copolymer C) is preferably composed of
70 - 99% by weight a),
0.1 - 12% by weight b),
0 - 6 wt% c) and
0 - 25% by weight d).

Copolymer B) very particularly preferably contains essentially no compound b) and copolymer C) essentially no compound c).

One of the two copolymers B) or C) has a higher molecular weight, characterized by a K value of 30 to 70, preferably 35 to 55 and the other copolymer has a K value of 12 to 40, preferably 15 to 30.

Copolymer C) very particularly preferably has the higher K value.

The K value of the two copolymers differs by at least 5, preferably by at least 15 K value units.

What has been said above (for copolymer A) applies to the glass transition temperature of copolymers B) and C).

Compounds A), B) and C) which can be used as compounds c) are those of the formula I or II or mixtures thereof.

Copolymers with a K value of 30 and larger preferably contain copolymerizable Si compounds of the formula I.

Copolymers with a K value below 30 preferably contain regulating Si compounds of the formula II or mixtures of Si compounds of the formulas I and II with at least 10% by weight, preferably at least 40% by weight of compounds II, based on the total content of compounds c).

The copolymers are prepared by radical polymerization, e.g. by bulk polymerization (solvent-free) or preferably in solution, generally at temperatures from 20 to 120, preferably from 80 to 120 ° C.

The solution polymerization can be carried out as a batch process or in the form of a feed process. The feed process is preferred, in which part of the polymerization batch is initially charged, heated to the polymerization temperature and then the rest is fed continuously.

As a solvent for radical solution polymerization, ethers such as tetrahydrofuran or dioxane, esters such as ethyl acetate or n-butyl acetate, ketones such as acetone or cyclohexanone, N, N-dialkylcarboxamides such as N, N-dimethylformamide, N, N-dimethylacetamide or N- Methyl 2-pyrrolidone, aromatics such as toluene and xylene, aliphatic hydrocarbons such as isooctane, chlorinated hydrocarbons such as tert-butyl chloride or plasticizers such as di-n-butyl phthalate are used.

Appropriately, one works in "anhydrous" polymerization medium, i.e. with a water content of less than 100 ppm. Advantageously, the solution polymerization of the per se anhydrous reactants in the presence of small amounts of drying agents such as tetraalkoxysilanes, e.g. Tetramethoxysilane or trialkyl orthoformate, e.g. Triethyl orthoformate, optionally with the addition of a Lewis acid. The solvent can be partially or completely separated from the solutions of the copolymers thus obtainable, for example by distillation in vacuo.

Preferred initiators are dibenzoyl peroxide, tert-butyl perpivalate, tert-butyl per-2-ethylhexanoate, di-tert-butyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, dilauryl peroxide, tert-butyl peroximaleinate, tert-butyl peroxibenzoate, didicanyl peroxide, dicumyl peroxide Methyl ethyl ketone peroxide, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,3-dimethylbutyronitrile) and 2,2'-azobisisobutyronitrile. Azo initiators carrying silane groups are also suitable (EP-A 159 710).

Copolymer A) or the mixture containing copolymer B) and C) is preferably used as a sealing, adhesive or coating material.

Sealants, adhesives and coating compositions which contain copolymer A) or a mixture of copolymers B) and C) as the polymer base are preferably essentially free of isocyanate compounds, ketimines or aldimines, such as those e.g. are mentioned in DE-A 40 38 939.

The sealing, adhesive and coating compositions are preferably one-component, i.e. no additives are required for hardening. Hardening is only effected by exposure to air humidity. However, catalysts, in particular dialkyltin dicarboxylates, e.g. Dibutyltin dilaurate can be added to the compositions in small amounts, generally in amounts of 0.05-2.0% by weight, based on the polymer composition. The masses can contain other conventional additives.

The compositions preferably contain no solvent or only residual amounts of solvent from the preparation of the copolymers in amounts below 5% by weight, preferably below 1% by weight, based on the compositions.

When mixing the components of the sealants, adhesives and coating compounds, as with the manufacture of the individual copolymers, care must be taken to exclude moisture. The sealing, adhesive and coating compositions are preferably in a sealed container e.g. Cartridges stored.

The sealing, adhesive and coating compositions according to the invention cure rapidly under the influence of atmospheric moisture.

The masses are generally stable in storage for longer than 6 months with the exclusion of moisture.

The masses are processed in the liquid state, in particular at temperatures from 10 to 100 ° C. They can be applied or pressed into cavities, after which hardening takes place through exposure to atmospheric moisture.

The substrates to be treated with the compositions are, for example those made of plastic, metal, concrete, ceramic or wood.

Due to their increased elasticity in the hardened state, the materials are used in particular to bridge cracks in the substrate or to fill in expansion joints. Outside compositions according to the invention based on copolymers with a glass transition temperature of from -10 to -40 ° C. are preferably used.

The sealing compounds according to the invention are notable for particularly good adhesion to glass, aluminum and ceramic. They can also be painted over with varnish.

Gas inclusions that cause problems with sealants containing isocyanate are avoided in the present invention. The compositions of the invention are therefore preferably suitable for use as a transparent sealant.

When cured, the compositions according to the invention have very good tensile strength and elongation at break.

Examples Abbreviations

BA:

n-butyl acrylate

MSA:

Maleic anhydride

MEMO:

Methacryloxypropyltrimethoxysilane

MTMO:

Mercaptopropyltrimethoxysilane

DBTL:

Dibutyltin dilaurate

Preparation of the copolymers Copolymer E1 Inlet 1:

770 g BA
80 g MSA

Inlet 2:

130 g BA
20 g MEMO

Inlet 3:

30 g of tert-butyl peroctoate
130 g toluene
Under an inert gas atmosphere, an initial charge consisting of a solution of 10% by weight of the monomer feed I and 10% by weight of an initiator feed III and 550 g of toluene was brought to an internal reactor temperature of 95 ° C. and polymerized for 10 minutes. The three feeds were then started, the monomer feed I consisting of the acrylic ester monomers and unsaturated anhydride in 3 h, the monomer feed II consisting of acrylic ester monomers and the silane compounds in 1 h and the initiator feed III consisting of 30 g of tert-butyl peroctoate and 130 g of toluene were fed in in 4 h. When the feeds had ended, the mixture was polymerized at 95 ° C. for 3 h and the solvent and volatile constituents were distilled off in vacuo.

In the case of blends with the DBTL accelerator or with other copolymers, the solvent was removed by distillation after the blending.

The other copolymers were prepared as described above (composition see Table 1). Table 1 Composition of the copolymers Copolymer Monomer% by weight Si monomer% by weight Si controller wt% K value V1 * 98 BA 2 MEMO - 31 E1 ** 90 BA, 8 MSA 2 MEMO - 30.5 E2 88 BA, 8 MSA 2 MEMO 2 MTMO 21.9 E3 88 BA, 8 MSA 2 MEMO 2 MTMO 21.9 E4 88 BA, 8 MSA 2 MEMO 2 MTMO 21.9 E5 88 BA, 8 MSA 2 MEMO 2 MTMO 21.9 E6 92 BA, 4 MSA 2 MEMO 2 MTMO 28.7 A1 *** 92 BA, 8 MSA - 37.0 * for comparison ** according to the invention *** for blends (see below)

Application test

The copolymers V1 and E1-E6 and copolymer mixtures in a weight ratio of 1: 1 and 2: 1 were tested for their suitability as a sealing compound.

To determine the elongation at break and tensile strength, 1 mm thick films were produced from the self-curable copolymers and mixtures by application to silicone paper and stored for 6 months in a standard atmosphere (23 ° C., 50% atmospheric humidity). Subsequently Test specimens were punched out of the films, after which the elongation at break and tensile strength according to DIN 53 504 were measured at a feed rate of 100 mm / min. Table 2 Copolymer or mixture Addition of DBTL% by weight * Tensile strength N / mm² Elongation at break% V1 - 0.092 147 E1 - 0.198 177 E2 - 0.153 187 E3 0.2 0.186 171 E4 0.6 0.192 164 E5 0.8 0.199 162 E6 - 0.142 191 E2 / A1 (1: 1) 0.2 0.356 323 E2 / A1 (2: 1) 0.2 0.486 363 * based on copolymer or mixture

Claims (6)

Essentially isocyanate-free, ketimine-free and aldimine-free, one-component sealing, adhesive or coating compositions, self-curing by the action of atmospheric moisture, containing a copolymer A, composed of
50 - 99.8% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids with 1 to 20 C atoms a)
0.1-20% by weight of an unsaturated carboxylic anhydride b)
0.1-10% by weight of an Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
or
containing a mixture of copolymers containing
5 - 95 wt .-%, based on the mixture, of a copolymer B), built up from
50-99.9% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids having 1 to 20 C atoms a),
0-20% by weight of an unsaturated carboxylic anhydride b)
0.1-10% by weight of an Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
and
5 - 95 wt .-%, based on the mixture, of a copolymer C), built up from
50-99.9% by weight of a C₁-C₁₆ alkyl (meth) acrylate or vinyl ester of carboxylic acids having 1 to 20 C atoms a),
0.1-20% by weight of an unsaturated carboxylic anhydride b)
0-10% by weight of a Si-containing compound c) and capable of hydrolysis
0 - 40% by weight of a further, copolymerizable unsaturated compound d)
where the K value measured according to DIN 53 726 of one of the copolymers B) or C) is 12 to 40 and the other copolymer 30 to 70 and the K value of the two copolymers differs by at least 5 K value units. A mixture of copolymers, self-curing under the influence of atmospheric moisture, each containing, based on the mixture,
5-95% by weight of the copolymer B) and
5 - 95% by weight of the copolymer C)
where the K value measured according to DIN 53 726 of one of the copolymers B) or C) is 12 to 40 and the other copolymer 30 to 70 and the K value of the two copolymers differs by at least 5 K value units. Sealing, adhesive or coating compositions or copolymer mixture according to claim 1 or 2, characterized in that c) are compounds of the general formulas

or mixtures thereof, where
R¹ for a C₁-C₁₈ alkyl group or a phenyl group, R² for a C₁-C₁₈ alkylene group, a cyclohexylene group or phenylene group, Z for a C₁-C₁₈ alkyl group or a phenyl group, X for a radical copolymerizable group and n for 0.1 or 2 stands. Under the action of atmospheric moisture self-curing copolymer A) according to claim 1, containing a compound of general formula I as Si-containing compound C). Sealants, adhesives or coating compositions or copolymer mixtures according to one of Claims 1 to 3, additionally containing dialkyltin dicarboxylates for accelerating self-hardening by the action of atmospheric moisture. Use of compositions containing a copolymer A or a mixture of copolymers B) and C) according to claim 2 or 4 by the action of atmospheric moisture self-curing coating, adhesive or coating compositions.